What percentage of users is that, assuming that you don't make parinfer the default choice in your IDE? What percentage of Cursive users knowingly say: I'm a bit confused by how these parens work (my guess: all lisp newcomers), what percentage goes to preferences to see what they can do about it (my educated guess: a lot, but less than, say, a third), and what percentage of those conciously look for parinfer (I don't know - I'm asking)?
Now, Cursive is used by something like a third of Clojure users. Half of them use Emacs, and in Emacs land there are rather few Clojurians who seek something like parinfer. Even when they do, it's a usual "how we can make this more palatable to outsiders" type of quest rather than "I'm really frustrated by how Emacs does Lisp editing. I'd like something like parinfer"...
I don't know exact numbers, since I don't do any user tracking. But I know of numerous users who are already experienced with Clojure who have switched, myself included. Cursive currently has paredit on by default, but I'm going to switch that to parinfer.
FWIW Emacs users do ask about parinfer in #parinfer on Clojurians because they actually want to use it. There currently isn't a smart mode for Emacs though, and that's what I consider the game changer. I suspect that uptake will be good once that's available.
Now, Cursive is used by something like a third of Clojure users. Half of them use Emacs, and in Emacs land there are rather few Clojurians who seek something like parinfer. Even when they do, it's a usual "how we can make this more palatable to outsiders" type of quest rather than "I'm really frustrated by how Emacs does Lisp editing. I'd like something like parinfer"...